The forecast for datacenters isn't good for the short term: they're going to get hotter and a lot more cramped, according to Gartner analysts.

Increasing use of cheaper x86 chip-based servers has presented problems for datacenters, most of which haven't been redesigned since the last tech boom went bust six years ago, said Rakesh Kumar, a Gartner research vice president. He spoke Monday during a presentation at Gartner's Data Center Technology Summit in London.

The number of server racks is increasing. Consequently, the amount of floor space in datacenters is decreasing, but their power and cooling requirements are rising.

"It will come down to a balance between the power, the cooling and the floor space," Kumar said. "What that means is legacy datacenters are obsolete."

Gartner predicts that within 12 to 18 months organizations will have to make major changes to accommodate the heating and cooling challenges that come with more processing power.

Four years ago, a stand-alone server in a rack used 2 kilowatts of electricity. Today, a standard rack filled with between 50 percent to 80 percent of blade servers consume between 15 kilowatts and 30 kilowatts per rack, Kumar said.

The cooling statistics complicate the power picture. It takes between 1.2 to 1.3 times the amount of energy a server consumes to cool it, Kumar said. IT managers frequently can't fill an entire rack because of the heat generated by the servers.

Floor cooling, where cool air is circulated under server racks, and air conditioning -- aren't going to work anymore because the heat is too great, Kumar said. What's more, the cool space beneath the servers in legacy datacenters becomes clogged with cables and wires and occasionally, other odd things that interfere.

"They're thinking 'Hey, there's space under here. I'll keep my beer in there,'" said Peter Hannaford, of American Power Conversion, which makes server cooling equipment. "We found this guy who had a Christmas tree under there."

All of these obstacles contribute to higher energy costs. Gartner estimates that electricity costs could go from 10 percent or less of IT budgets to 20 percent to 30 percent if left unchecked, Kumar said. Electricity costs have risen over the last year and will likely continue to rise, although the peak is unknown.

Fortunately, everyone from chip vendors to servers vendors and software makers have a stake in reducing energy and heat, Kumar said. The problem could ultimately limit the growth of IT. A huge amount of investment is being made in finding solutions, either through new products or through new datacenter designs.

Governments also are paying increased attention to IT. It's possible high-energy users could see higher taxes, or that ill-fitting legislation could be implemented, spurred by public demand for greener IT, said Steve Prentice, vice president and chief of research for Gartner.

"They [the government] will rush something in that apparently does the job but does not address all the issues," Prentice said. "We think it's better to self-regulate."